Articles de revistahttp://hdl.handle.net/2117/3954
Sat, 10 Dec 2016 01:14:03 GMT2016-12-10T01:14:03ZCO oxidation and COPrOx over preformed Au nanoparticles supported over nanoshaped CeO2http://hdl.handle.net/2117/97815
CO oxidation and COPrOx over preformed Au nanoparticles supported over nanoshaped CeO2
Soler Turu, Lluís; Casanovas Grau, Albert; Urrich, Aitor; Angurell Purroy, Inmaculada; Llorca Piqué, Jordi
Au/CeO2 (0.25% wt. Au) catalysts were prepared by anchoring preformed Au nanoparticles over ceria polycrystals, cubes and rods and tested in the oxidation of CO and COPrOx. The use of preformed Au nanoparticles assured a constant Au particle size (ca. 5 nm by HRTEM) for all samples, which allowed to a precise assessment of the effect of the morphology of nanoshaped ceria on catalytic activity. The catalytic performance of the Au/CeO2-rods was much better than that of the Au/CeO2-polycrystals and Au/CeO2-cubes both in the oxidation of CO and COPrOx reactions. The Au/CeO2-rods exhibited the highest amount of oxidized Au and Ce(III) species by XPS, whereas in the Au/CeO2-cubes gold was totally metallic and the amount of Ce(III) was minimum. An intermediate situation was encountered in the Au/CeO2-polycrystals. Considering the differences in the oxidation states ofAu and Ce and the factthat all samples were prepared
with preformed metallic Au nanoparticles of the same size, the results indicate that the intrinsic nature of the different ceria surfaces exerts a prominent role in the gold-ceria interaction and in the electron density transfer from Au to Ce, which in turn has a strong effect on catalytic activity. Gold nanoparticles strongly interact with CeO2-{1 1 0} surfaces with respect to CeO2-{1 1 1} and CeO2-{1 0 0}, even when Au nanoparticles are prepared separately and simply deposited by impregnation.
Mon, 05 Dec 2016 17:58:49 GMThttp://hdl.handle.net/2117/978152016-12-05T17:58:49ZSoler Turu, LluísCasanovas Grau, AlbertUrrich, AitorAngurell Purroy, InmaculadaLlorca Piqué, JordiAu/CeO2 (0.25% wt. Au) catalysts were prepared by anchoring preformed Au nanoparticles over ceria polycrystals, cubes and rods and tested in the oxidation of CO and COPrOx. The use of preformed Au nanoparticles assured a constant Au particle size (ca. 5 nm by HRTEM) for all samples, which allowed to a precise assessment of the effect of the morphology of nanoshaped ceria on catalytic activity. The catalytic performance of the Au/CeO2-rods was much better than that of the Au/CeO2-polycrystals and Au/CeO2-cubes both in the oxidation of CO and COPrOx reactions. The Au/CeO2-rods exhibited the highest amount of oxidized Au and Ce(III) species by XPS, whereas in the Au/CeO2-cubes gold was totally metallic and the amount of Ce(III) was minimum. An intermediate situation was encountered in the Au/CeO2-polycrystals. Considering the differences in the oxidation states ofAu and Ce and the factthat all samples were prepared
with preformed metallic Au nanoparticles of the same size, the results indicate that the intrinsic nature of the different ceria surfaces exerts a prominent role in the gold-ceria interaction and in the electron density transfer from Au to Ce, which in turn has a strong effect on catalytic activity. Gold nanoparticles strongly interact with CeO2-{1 1 0} surfaces with respect to CeO2-{1 1 1} and CeO2-{1 0 0}, even when Au nanoparticles are prepared separately and simply deposited by impregnation.Nuclear data activities at the n_TOF facility at CERNhttp://hdl.handle.net/2117/97254
Nuclear data activities at the n_TOF facility at CERN
Gunsing, Frank; Aberle, O.; Andrzejewski, Józef; Calviño Tavares, Francisco; Casanovas Hoste, Adrià; Cortés Rossell, Guillem Pere; Riego-Pérez, albert; Tarifeño Saldivia, Ariel Esteban
Nuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. Experimental nuclear reaction data are compiled on a worldwide basis by the international network of Nuclear Reaction Data Centres (NRDC) in the EXFOR database. The EXFOR database forms an important link between nuclear data measurements and the evaluated data libraries. CERN's neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of the scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at CERN's neutron time-of-flight facility n_TOF will be presented.
Fri, 25 Nov 2016 12:34:07 GMThttp://hdl.handle.net/2117/972542016-11-25T12:34:07ZGunsing, FrankAberle, O.Andrzejewski, JózefCalviño Tavares, FranciscoCasanovas Hoste, AdriàCortés Rossell, Guillem PereRiego-Pérez, albertTarifeño Saldivia, Ariel EstebanNuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. Experimental nuclear reaction data are compiled on a worldwide basis by the international network of Nuclear Reaction Data Centres (NRDC) in the EXFOR database. The EXFOR database forms an important link between nuclear data measurements and the evaluated data libraries. CERN's neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of the scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at CERN's neutron time-of-flight facility n_TOF will be presented.Be-7(n,alpha)He-4 reaction and the cosmological lithium problem: measurement of the cross section in a wide energy range at n_TOF at CERNhttp://hdl.handle.net/2117/97084
Be-7(n,alpha)He-4 reaction and the cosmological lithium problem: measurement of the cross section in a wide energy range at n_TOF at CERN
Barbagallo, Massimo; Musumarra, A.; Cosentino, L.; Calviño Tavares, Francisco; Casanovas Hoste, Adrià; Cortés Rossell, Guillem Pere; Tarifeño Saldivia, Ariel Esteban
The energy-dependent cross section of the Be7(n,alpha)He4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be7 and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure Be7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.
Wed, 23 Nov 2016 09:49:13 GMThttp://hdl.handle.net/2117/970842016-11-23T09:49:13ZBarbagallo, MassimoMusumarra, A.Cosentino, L.Calviño Tavares, FranciscoCasanovas Hoste, AdriàCortés Rossell, Guillem PereTarifeño Saldivia, Ariel EstebanThe energy-dependent cross section of the Be7(n,alpha)He4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be7 and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure Be7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.Three-dimensional ruthenium-doped TiO2 sea urchins for enhanced visible-light-responsive H-2 productionhttp://hdl.handle.net/2117/90155
Three-dimensional ruthenium-doped TiO2 sea urchins for enhanced visible-light-responsive H-2 production
Thuy Duong, Nguyen-Phan; Luo, Si; Vovchok, Dimitriy; Llorca Piqué, Jordi; Sallis, Shawn; Kattel, Shyam; Xu, Wenqian; Piper, Louis F. J.; Poliansky, Dimitry E.; Senanayake, Sanjaya D.; Stacchiola, Darío J.; Rodriguez, Jose A.
Three-dimensional (3D) monodispersed sea urchin-like Ru-doped rutile TiO2 hierarchical architectures composed of radially aligned, densely-packed TiO2 nanorods have been successfully synthesized via an acid-hydrothermal method at low temperature without the assistance of any structure-directing agent and post annealing treatment. The addition of a minuscule concentration of ruthenium dopants remarkably catalyzes the formation of the 3D urchin structure and drives the enhanced photocatalytic H-2 production under visible light irradiation, not possible on undoped and bulk rutile TiO2. Increasing ruthenium doping dosage not only increases the surface area up to 166 m(2) g(-1) but also induces enhanced photoresponse in the regime of visible and near infrared light. The doping introduces defect impurity levels, i.e. oxygen vacancy and under-coordinated Ti3+, significantly below the conduction band of TiO2, and ruthenium species act as electron donors/acceptors that accelerate the photogenerated hole and electron transfer and efficiently suppress the rapid charge recombination, therefore improving the visible-light-driven activity.
Fri, 23 Sep 2016 09:48:09 GMThttp://hdl.handle.net/2117/901552016-09-23T09:48:09ZThuy Duong, Nguyen-PhanLuo, SiVovchok, DimitriyLlorca Piqué, JordiSallis, ShawnKattel, ShyamXu, WenqianPiper, Louis F. J.Poliansky, Dimitry E.Senanayake, Sanjaya D.Stacchiola, Darío J.Rodriguez, Jose A.Three-dimensional (3D) monodispersed sea urchin-like Ru-doped rutile TiO2 hierarchical architectures composed of radially aligned, densely-packed TiO2 nanorods have been successfully synthesized via an acid-hydrothermal method at low temperature without the assistance of any structure-directing agent and post annealing treatment. The addition of a minuscule concentration of ruthenium dopants remarkably catalyzes the formation of the 3D urchin structure and drives the enhanced photocatalytic H-2 production under visible light irradiation, not possible on undoped and bulk rutile TiO2. Increasing ruthenium doping dosage not only increases the surface area up to 166 m(2) g(-1) but also induces enhanced photoresponse in the regime of visible and near infrared light. The doping introduces defect impurity levels, i.e. oxygen vacancy and under-coordinated Ti3+, significantly below the conduction band of TiO2, and ruthenium species act as electron donors/acceptors that accelerate the photogenerated hole and electron transfer and efficiently suppress the rapid charge recombination, therefore improving the visible-light-driven activity.First tests of the applicability of gamma-ray imaging for background discrimination in time-of-flight neutron capture measurementshttp://hdl.handle.net/2117/90017
First tests of the applicability of gamma-ray imaging for background discrimination in time-of-flight neutron capture measurements
Perez Magan, D. L.; Caballero Ontanaya, L.; Domingo Pardo, César; Agramunt Ros, Jorge; Albiol, F.; Casanovas Grau, Albert; Gonzalez, A.; Guerrero, C.; Lerendegui Marco, J.; Tarifeño Saldivia, Ariel Esteban
In this work we explore for the first time the applicability of using gamma-ray imaging in neutron capture measurements to identify and suppress spatially localized background. For this aim, a pinhole gamma camera is assembled, tested and characterized in terms of energy and spatial performance. It consists of a monolithic CeBr3 scintillating crystal coupled to a position-sensitive photomultiplier and readout through an integrated circuit AMIC2GR. The pinhole collimator is a massive carven block of lead. A series of dedicated measurements with calibrated sources and with a neutron beam incident on a Au-197 sample have been carried out at n_TOF, achieving an enhancement of a factor of two in the signal-to-background ratio when selecting only those events coming from the direction of the sample. (C) 2016 Elsevier B.V. All rights reserved.
Mon, 19 Sep 2016 09:48:12 GMThttp://hdl.handle.net/2117/900172016-09-19T09:48:12ZPerez Magan, D. L.Caballero Ontanaya, L.Domingo Pardo, CésarAgramunt Ros, JorgeAlbiol, F.Casanovas Grau, AlbertGonzalez, A.Guerrero, C.Lerendegui Marco, J.Tarifeño Saldivia, Ariel EstebanIn this work we explore for the first time the applicability of using gamma-ray imaging in neutron capture measurements to identify and suppress spatially localized background. For this aim, a pinhole gamma camera is assembled, tested and characterized in terms of energy and spatial performance. It consists of a monolithic CeBr3 scintillating crystal coupled to a position-sensitive photomultiplier and readout through an integrated circuit AMIC2GR. The pinhole collimator is a massive carven block of lead. A series of dedicated measurements with calibrated sources and with a neutron beam incident on a Au-197 sample have been carried out at n_TOF, achieving an enhancement of a factor of two in the signal-to-background ratio when selecting only those events coming from the direction of the sample. (C) 2016 Elsevier B.V. All rights reserved.Dynamic modeling and controllability analysis of an ethanol reformer for fuel cell applicationhttp://hdl.handle.net/2117/89384
Dynamic modeling and controllability analysis of an ethanol reformer for fuel cell application
García, Vanesa Mariel; Lopez Null, Eduardo; Serra, Maria; Llorca Piqué, Jordi; Riera Colomer, Jordi
This work presents a controllability analysis of a low temperature ethanol reformer based on a cobalt catalyst for fuel cell application. The study is based on a nonlinear dynamic model of a reformer which operates in three separate stages: ethanol dehydrogenation to acetaldehyde and hydrogen, acetaldehyde steam reforming, and water gas shift reaction. The controllability anal
ysis is focused on the rapid dynamics due to mass balances and is based on a linear
ization of the complex non-linear model of the reformer. RGA, CN and MRI analysis tools are applied to the linear model suggesting that a good performance can be
obtained with decentralized control for frequencies up to 0.1 rad/s.
Wed, 24 Aug 2016 12:41:35 GMThttp://hdl.handle.net/2117/893842016-08-24T12:41:35ZGarcía, Vanesa MarielLopez Null, EduardoSerra, MariaLlorca Piqué, JordiRiera Colomer, JordiThis work presents a controllability analysis of a low temperature ethanol reformer based on a cobalt catalyst for fuel cell application. The study is based on a nonlinear dynamic model of a reformer which operates in three separate stages: ethanol dehydrogenation to acetaldehyde and hydrogen, acetaldehyde steam reforming, and water gas shift reaction. The controllability anal
ysis is focused on the rapid dynamics due to mass balances and is based on a linear
ization of the complex non-linear model of the reformer. RGA, CN and MRI analysis tools are applied to the linear model suggesting that a good performance can be
obtained with decentralized control for frequencies up to 0.1 rad/s.In situ photoelectron spectroscopy study of ethanol steam reforming over RhPd nanoparticles and RhPd/CeO2http://hdl.handle.net/2117/89316
In situ photoelectron spectroscopy study of ethanol steam reforming over RhPd nanoparticles and RhPd/CeO2
Jiménez Divins, Nuria; Llorca Piqué, Jordi
In situ X-ray photoelectron spectroscopy (XPS) was carried out over model Rh0.5Pd0.5 nanoparticles and Rh0.5Pd0.5 nanoparticles supported on CeO2 following exposure to oxygen at 573-823 K, to hydrogen at 573 K (activation of the catalyst), to a mixture of ethanol and water at 823 K simulating ethanol steam reforming (ESR) conditions, and to hydrogen at 823 K. The presence of the CeO2 support had a strong influence on the atomic rearrangement and on the oxidation state of Rh0.5Pd0.5 nanoparticles. CeO2 exerted a quenching effect on the metal nanoparticles and limited atomic rearrangement under the different atmospheres tested except for ESR, where a partial segregation of Rh toward the surface of the nanoparticles was observed. When supported on CeO2, Rh0.5Pd0.5 nanoparticles were significantly more oxidized due to metal-support interaction. By comparing these in situ XPS results with a previous operando near ambient pressure XPS study conducted in a synchrotron facility at 0.05 mbar over the same samples, it is concluded that the information obtained for the unsupported Rh0.5Pd0.5 nanoparticles is similar in both cases, whereas Rh0.5Pd0.5 nanoparticles supported on CeO2 are clearly more oxidized and enriched in Pd in the volume sampled under operando ESR conditions compared to that obtained in the in situ experiments. The study of catalytic systems under operando conditions appears essential to identify the active species at work during ESR, as the restructuring driven by the reforming environment induces strong changes in their architecture. (C) 2015 Elsevier B.V. All rights reserved.
Thu, 28 Jul 2016 09:59:55 GMThttp://hdl.handle.net/2117/893162016-07-28T09:59:55ZJiménez Divins, NuriaLlorca Piqué, JordiIn situ X-ray photoelectron spectroscopy (XPS) was carried out over model Rh0.5Pd0.5 nanoparticles and Rh0.5Pd0.5 nanoparticles supported on CeO2 following exposure to oxygen at 573-823 K, to hydrogen at 573 K (activation of the catalyst), to a mixture of ethanol and water at 823 K simulating ethanol steam reforming (ESR) conditions, and to hydrogen at 823 K. The presence of the CeO2 support had a strong influence on the atomic rearrangement and on the oxidation state of Rh0.5Pd0.5 nanoparticles. CeO2 exerted a quenching effect on the metal nanoparticles and limited atomic rearrangement under the different atmospheres tested except for ESR, where a partial segregation of Rh toward the surface of the nanoparticles was observed. When supported on CeO2, Rh0.5Pd0.5 nanoparticles were significantly more oxidized due to metal-support interaction. By comparing these in situ XPS results with a previous operando near ambient pressure XPS study conducted in a synchrotron facility at 0.05 mbar over the same samples, it is concluded that the information obtained for the unsupported Rh0.5Pd0.5 nanoparticles is similar in both cases, whereas Rh0.5Pd0.5 nanoparticles supported on CeO2 are clearly more oxidized and enriched in Pd in the volume sampled under operando ESR conditions compared to that obtained in the in situ experiments. The study of catalytic systems under operando conditions appears essential to identify the active species at work during ESR, as the restructuring driven by the reforming environment induces strong changes in their architecture. (C) 2015 Elsevier B.V. All rights reserved.Silicone microreactors for the photocatalytic generation of hydrogenhttp://hdl.handle.net/2117/89310
Silicone microreactors for the photocatalytic generation of hydrogen
Castedo Rodríguez, Alejandra; Mendoza Gómez, Ernesto; Angurell Purroy, Inmaculada; Llorca Piqué, Jordi
A silicone microreactor with 500 mu m-width microchannels coated with a Au/TiO2 photocatalyst was manufactured and tested for the photocatalytic generation of hydrogen from gaseous water-ethanol mixtures under dynamic conditions. The manufacture of the microreactor included the fabrication of a polylactic acid (PLA) mold with a 3D printer and casting with polydimethylsiloxane (PDMS) prepolymer. After curing, the silicone microreactor was peeled off and the microchannels were coated with a Au/TiO2 photocatalyst prepared by impregnation of preformed Au nanoparticles over TiO2, and sealed with a thin silicone cover. The microreactor was tested at room temperature and atmospheric pressure under different operational conditions (photon irradiance, residence time, photocatalyst loading, and water ethanol ratio). Hydrogen production rates of 5.4 NmL W-1 h(-1) were measured at a residence time of 0.35 s using a H2O:C2H5OH molar ratio of 9:1, a photocatalyst load of 1.2 mg cm(-2) and a UV irradiance (365 nm) of 1.5 mW cm(-2) achieving an apparent quantum efficiency of 9.2%. The photogeneration of hydrogen with commercial bioethanol was also tested. A long-term photocatalytic test of two days revealed a stable hydrogen photoproduction rate. The use of silicone microreactors represents an attractive and customizable solution for conducting photochemical reactions for producing hydrogen at low cost. (C) 2016 Elsevier B.V. All rights reserved.
Thu, 28 Jul 2016 09:41:59 GMThttp://hdl.handle.net/2117/893102016-07-28T09:41:59ZCastedo Rodríguez, AlejandraMendoza Gómez, ErnestoAngurell Purroy, InmaculadaLlorca Piqué, JordiA silicone microreactor with 500 mu m-width microchannels coated with a Au/TiO2 photocatalyst was manufactured and tested for the photocatalytic generation of hydrogen from gaseous water-ethanol mixtures under dynamic conditions. The manufacture of the microreactor included the fabrication of a polylactic acid (PLA) mold with a 3D printer and casting with polydimethylsiloxane (PDMS) prepolymer. After curing, the silicone microreactor was peeled off and the microchannels were coated with a Au/TiO2 photocatalyst prepared by impregnation of preformed Au nanoparticles over TiO2, and sealed with a thin silicone cover. The microreactor was tested at room temperature and atmospheric pressure under different operational conditions (photon irradiance, residence time, photocatalyst loading, and water ethanol ratio). Hydrogen production rates of 5.4 NmL W-1 h(-1) were measured at a residence time of 0.35 s using a H2O:C2H5OH molar ratio of 9:1, a photocatalyst load of 1.2 mg cm(-2) and a UV irradiance (365 nm) of 1.5 mW cm(-2) achieving an apparent quantum efficiency of 9.2%. The photogeneration of hydrogen with commercial bioethanol was also tested. A long-term photocatalytic test of two days revealed a stable hydrogen photoproduction rate. The use of silicone microreactors represents an attractive and customizable solution for conducting photochemical reactions for producing hydrogen at low cost. (C) 2016 Elsevier B.V. All rights reserved.Study of the effect of the chromophore and nuclearity on the aggregation and potential biological activity of gold(I) alkynyl complexeshttp://hdl.handle.net/2117/89213
Study of the effect of the chromophore and nuclearity on the aggregation and potential biological activity of gold(I) alkynyl complexes
Gavara, Raquel; Aguilo, Elisabet; Schur, Julia; Llorca Piqué, Jordi; Ott, Ingo; Rodríguez Raurell, Laura
The synthesis and characterization of four organometallic gold(I) complexes containing different water soluble phosphanes (TPPTS, PTA and DAPTA) and chromophoric units (4-pyridylethynyl and propargyloxycoumarin) is here reported. The analysis of their absorption and emission spectra led us to attribute their luminescent behavior to the chromophoric organic ligands. Moreover, the presence of the gold(I) metal atom has been observed to be the responsible of an efficient intersystem crossing process responsible for the observed phosphorescence emission. Broad emission bands are observed in most cases due to the formation of organized aggregates in solution in agreement with microscopic characterization.; Biological activity of the complexes showed very low effects against tumor cell growth but an inhibitory potency against thioredoxin reductase (TrxR). The missing/low cytotoxic effects could be related to a low bioavailability as determined by atomic absorption spectroscopy. (C) 2016 Elsevier B.V. All rights reserved.
Tue, 26 Jul 2016 10:59:55 GMThttp://hdl.handle.net/2117/892132016-07-26T10:59:55ZGavara, RaquelAguilo, ElisabetSchur, JuliaLlorca Piqué, JordiOtt, IngoRodríguez Raurell, LauraThe synthesis and characterization of four organometallic gold(I) complexes containing different water soluble phosphanes (TPPTS, PTA and DAPTA) and chromophoric units (4-pyridylethynyl and propargyloxycoumarin) is here reported. The analysis of their absorption and emission spectra led us to attribute their luminescent behavior to the chromophoric organic ligands. Moreover, the presence of the gold(I) metal atom has been observed to be the responsible of an efficient intersystem crossing process responsible for the observed phosphorescence emission. Broad emission bands are observed in most cases due to the formation of organized aggregates in solution in agreement with microscopic characterization.; Biological activity of the complexes showed very low effects against tumor cell growth but an inhibitory potency against thioredoxin reductase (TrxR). The missing/low cytotoxic effects could be related to a low bioavailability as determined by atomic absorption spectroscopy. (C) 2016 Elsevier B.V. All rights reserved.Magnetite-supported palladium single-atoms do not catalyse the hydrogenation of alkenes but small clusters dohttp://hdl.handle.net/2117/89199
Magnetite-supported palladium single-atoms do not catalyse the hydrogenation of alkenes but small clusters do
Rosell, Marta D.; Caparrós, Francisco J.; Angurell Purroy, Inmaculada; Müller Jevenois, Guillermo; Llorca Piqué, Jordi; Seco García, Miquel Angel; Rosell, Oriol
The activity of supported noble metal catalysts strongly depends on the particle size. The ultimate small-size limit is the single-atom catalyst (SAC), which maximizes the catalytic efficiency in the majority of the examples. Here, we investigate the catalytic behavior of Pd SACs supported on magnetite nanoparticles and we unambiguously demonstrate that Pd SACs are absolutely inactive in the hydrogenation of various alkene substrates. Instead, Pd clusters of low atomicity exhibit outstanding catalytic performance.
Tue, 26 Jul 2016 09:59:31 GMThttp://hdl.handle.net/2117/891992016-07-26T09:59:31ZRosell, Marta D.Caparrós, Francisco J.Angurell Purroy, InmaculadaMüller Jevenois, GuillermoLlorca Piqué, JordiSeco García, Miquel AngelRosell, OriolThe activity of supported noble metal catalysts strongly depends on the particle size. The ultimate small-size limit is the single-atom catalyst (SAC), which maximizes the catalytic efficiency in the majority of the examples. Here, we investigate the catalytic behavior of Pd SACs supported on magnetite nanoparticles and we unambiguously demonstrate that Pd SACs are absolutely inactive in the hydrogenation of various alkene substrates. Instead, Pd clusters of low atomicity exhibit outstanding catalytic performance.